Method for constructing dynamic multifocal superlens based on medium and graphene

Abstract

The invention discloses a method for constructing a dynamic multifocal superlens based on a medium and graphene. The method includes the following steps that: (1) as for incident light of different wavelengths, phase gradient distribution on a medium metasurface within an infrared wavelength range of 0.7 micron to 500 microns is calculated according to positional relations between focuses and wavelengths; (2) different periodic structures are designed for each center wavelength, specific phase values are determined according to the phase gradient distribution and Pancharatnam-Berry phases; (3)height-determined columnar structures are designed as the basic units of the medium metasurface, and then, a corresponding concrete realization structure and rotation direction are designed; and (4)according to a substrate part, multilayer graphene is adopted to form a reflection type focusing lens, and the Fermi level of the graphene can be changed such the position of a focusing point can be dynamically adjusted. According to the method of the invention, the dynamic multifocal reflective lens is realized through the medium metasurface and the multilayer graphene structure. The method has the advantages of high-efficiency focusing function, ultra-wideband performance, dynamic adjustment, easiness in integration and the like.

Description

(1) Technical field [0001] The invention relates to a method for constructing a dynamic multi-focus hyperlens based on a medium and graphene, and belongs to the fields of geometric optics and micro-nano optics. (2) Background technology [0002] As a subwavelength structure arranged on a two-dimensional surface, metasurfaces have been rapidly developed due to their special functions of locally changing the amplitude, polarization, and phase of incident light beams. Therefore, lenses designed based on metasurfaces have also attracted widespread attention. Unlike traditional lenses, this metasurface optical lens is based on optical nanomaterials, so it is relatively light. When the metasurface's subwavelength nanostructures form specific repeating patterns, they mimic the complex curvature of refracted light, but are less bulky and have an improved ability to focus light with reduced distortion. However, most such nanostructured devices are static, thus limiting their functio...

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Problems solved by technology

However, most such nanostructured devices are static, thus limiting their functionality

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